Various display technologies may display computer generated images, such as three-dimensional holograms or two-dimensional images, to create an immersive virtual reality or augmented reality viewing experience. For example, some stereoscopic display devices, such as head-mounted display (HMD) devices, may comprise a see-through display that allows superposition of images over a real-world environment. The images may appear integrated with the real-world environment when viewed through the see-through display of the HMD device. Such a relationship between virtual images and the real-world environment may be referred to as augmented reality.
Where an image is generated by a stereoscopic display, light comprising the image originates at a display screen or other surface and travels to the eyes of the viewer over an actual viewing distance. In some examples, the light may be controlled to create a viewer-perceived location of the image at a distance from the viewer that is different from the actual viewing distance of the display screen or surface. For example, an HMD device displays images that are perceived by the viewer to be at distance from the viewer's eyes that is greater than the eye relief distance between eyes and the HMD screen or lens.
In some examples, a viewer may approach a computer generated image to appreciate image details or otherwise interact with the image. In other examples an image may be displayed to move closer to the viewer. It has been discovered, however, that as the distance between the viewer and a perceived location of the image decreases, at certain distances some viewers may experience discomfort such as dizziness, headaches, double vision and/or other issues. Because of these viewer comfort issues, some display devices may impose a minimum viewing distance that limits the perceived proximity of a displayed image. Unfortunately, such minimum viewing distances may prevent viewers from more closely approaching an image, and may thereby limit interactive experiences and related features of augmented or virtual reality applications. Additionally, such minimum viewing distances negatively impact the viewing experiences of viewers who are not affected by viewing comfort issues.